Time-Reassigned Multisynchrosqueezing S-Transform for Bearing Fault Diagnosis

Time-frequency analysis (TFA) is an important tool to detect the condition of rotating machinery. However, the traditional TFA methods are difficult to extract the transient characteristics of vibration signals. In the article, a sparse TFA method called time-reassigned multisynchronosqueezing S-transform (TMSSST) is proposed. This method, combining the frequency self-adaptability of S-transform (ST) and the iteration operation of the multisynchronosqueezing algorithm, overcomes the limitation of the fixed sliding widow in short-time Fourier transform (STFT) and achieves a time-frequency representation (TFR) with higher energy concentration. Moreover, the theoretical analysis of group delay operator (GDO) and reversibility are discussed, which concludes that the proposed method can approximate the group delay of transient signals and support signal reconstruction. To verify the effectiveness of the TMSSST method, the simulated signal and experimental signal of bearing fault are tested, respectively. The comparison results with the existing methods show the superiority and robustness of the proposed method in bearing fault diagnosis.